Desired device dimensions and pitches have decreased to the point where traditional single patterning photolithographic techniques (e.g., 193 nm wavelength photolithography) cannot form a single patterned mask layer with all of the features of the final target pattern. Thus, device designers and manufacturers have begun utilizing various double patterning techniques, such as self-aligned double patterning (SADP). However, block masking in SADP adversely impacts metal routing because of inner vertex (or inner corner) rounding. In particular, block masking requires enforcement of minimum distances with respect to line ends.
A need therefore exists for a methodology and a corresponding apparatus legalizing routing configurations adversely impacted by inner corner rounding.